Ever since the political vulnerability of this nation's largely foreign controlled petroleum sources became painfully obvious in the early 1970's, there has been an intensive effort devoted to the development of alternative energy sources and conservation of existing resources. In more recent years, the acute nature of the energy problem has been underscored by a growing public awareness of the related environmental questions.
To a large extent, efforts aimed at energy conservation and alternative energy generation have met with a large degree of success in such areas as the heating and cooling of structures, automobile efficiency and the like. More particularly, large advances have been made by designing hotter running gasoline engines, use of reflective glazing, impermeable construction barriers, solar heating and the like.
However, one technology which has largely failed to live up to its very promising expectations is the use of hydrogen for the generation of electricity. Generally, this technology involves the utilization of hydrogen in electrochemical reaction for the purpose of generating electricity. A device in which such a process is carried out is generally referred to as a fuel cell. Because the electricity is generated by the reaction of hydrogen with oxygen, the only reaction emission involved is water vapor which is harmless to the environment. This may be compared to gasoline combustion which involves the release of hydrocarbons, carbon monoxide, and complex chemical species into the environment (along with the primary emissions, carbon dioxide and water vapor).
While it has been known that fuel cells offer many advantages as compared to other power sources, particularly in supplying power at remote locations (such as outer space or the like) and offer at least, in principle, limited service and maintenance requirements, various problems are presented by existing fuel cell technology. Nevertheless, perhaps the most advantageous fuel cell systems presently available (for certain applications, at least) are those which utilize a so-called proton-exchange membrane (PEM) electrolyte. Generally, in systems such as this, the electrolyte is embodied in the form of a synthetic polymeric material which acts as an electrolyte while still having the characteristic of being a solid body.
This type of system offers numerous advantages. For example, since the electrolyte phase is solid, no operational complications arise from migration of electrolytic material into adjacent regions of the fuel cell. At the same time, the system is mechanically stable and hardy under a wide variety of operating conditions. Moreover, such fuel cells have the ability to operate at or near room temperature and thus provide virtually instantaneous start-up. In principle, such systems offer the possibility that thermal management may be passively achieved, although practical implementation of this in a wide variety of designs may pose difficult design problems. One such fuel cell is described in Adlhart U.S. Pat. No. 4,175,165 which discloses a stack of grooved bipolar cell plates bolted together and secured with tension straps, a heavy and bulky construction designed to prevent fuel leakage.
Wilson et al. in "High Performance Catalyzed Membranes of Ultra-Low Pt Loadings for Polymer Electrolyte Fuel Cells" J. Electrochem. Soc. vol. 139 No. 2 February 1992 disclose catalyst film and electrolytic membrane structures useful in the practice of this invention.
Vanderborgh et al. in a paper prepared for Belvoir Research, Development and Engineering Center, Fort Belvoir, Va. entitled "ANALYSIS OF FUEL CELLS, REACTANT DELIVERY SYSTEMS, AND SYSTEM INTEGRATION FOR INDIVIDUAL POWER SOURCES", numbered "LA-UR-93-345" discuss and disclose ancillary systems and engineering, relating in particular to management of fluids such as coolant air, source gases and moisture, which teaching can also be useful when practicing certain embodiments of this invention.